This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian. You just brought home a kitten that you intend to name Sam but your roommate tells you that you had better consider the name Samantha instead. Lift the kitten's tail.
Kitten genitals are not as developed as adult cats, making gender determination a crapshoot. Don't disrupt the mother-kitten flow within the first few weeks of life. If a kitten is handled too much during this time, the mother may abandon it and stop nursing it altogether. So don't get too anxious to determine the sex of your kittens. Instead, wait until at least two weeks—or preferably longer—to start handling your kittens.
Forget about waiting 40 weeks to find out the sex of your baby. Practically since the beginning of time, moms-to-be and the people who love them have come up with ways to try to figure out if that bun in the oven is a girl or a boy. This semi-invasive procedure is a slam-dunk way to know your baby's gender for sure, but because of the small risk of miscarriage your doc probably won't green-light it for curiosity alone. Generations of women swear that a quick fetal heart rate — about beats per minute or above — signals girl, while below that equals boy.